2. Neil Armstrong

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When Kennedy made that declaration, he also acknowledged its challenges, calling the space program "the most hazardous and dangerous and greatest adventure on which man has ever embarked." Armstrong was accustomed to danger — he'd flown in Korea, and as an experimental test pilot — but the 1969 moon landing was a new kind of milestone, a defining event for humanity, and the significance of its imagery is inexpressible. The medium on which it was broadcast made it a shared human experience, as significant as Kennedy's assassination, but redemptive, the improbable realization of his promise to land on the moon within the decade.